Building an SVG Radar Chart by Hand

Positioning Points Around the Circle

Each variable in a radar chart gets an equal angular slice of the full circle, so its spoke angle is its index divided by the total count times two pi, and a point's position comes from multiplying that angle's cosine and sine by the scaled data value as a radius.

• Each variable's spoke angle is its index over total count times two pi
• The scaled data value becomes the radius along that spoke
• Multiplying the angle's cosine and sine by that radius gives x and y

Connecting Points into a Closed Shape

Once every variable's point is computed, connecting them produces the chart's characteristic shape, most simply by emitting a polygon element whose points attribute lists each coordinate pair in order, which closes the shape automatically without needing an explicit closing command.

• A polygon element's points attribute lists each coordinate pair in order
• Polygon automatically closes the shape without an explicit close command
• The resulting outline is the radar chart's characteristic web shape

Frequently Asked Questions

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